Electronic devices, such as integrated circuit chips, are commonly attached to a substrate (e.g., a printed circuit board (PCB) or printed circuit card (PCC)) with solder ball connecters using a ball grid array (BGA) connection technique. As known in the art, BGA generally involves the attachment of an array of solder balls located on the underside of an electronic device to a corresponding array of contact pads located on a surface of a substrate, using individual solder joints. Typically, each of the contact pads on the surface of the substrate is connected to a via that provides an electrically conductive path between the electronic device and wiring patterns located within internal layers of the substrate. The via may comprise, for example, a plated through hole (PTH), wherein the through hole extends through the thickness of the substrate and is lined with an electrically conductive material, or similar structure. A contact pad may be electrically connected to a via by a "dog-bone" or other type of connection, or may comprise a portion of the via itself. In the latter case, the contact pad or "via pad" generally extends above the top surface of the substrate directly above the via. The use of such "direct via" connections allows a designer to increase the density of electronic devices connected to a circuit board.
Typically, a low melting temperature eutectic solder paste, an electrically conductive adhesive, or other suitable material, is used to connect the solder balls on the electronic device to the via pads on the substrate. Unfortunately, a problem may occur when a solder ball connection is made to a via pad using a conventional "direct via" connection technique. Specifically, as the low melting temperature eutectic solder paste is heated and melts to form a connection between a solder ball and a via pad, the solder may be pulled down by a "wicking" action into the via away from the connection point. As a result of the wicking action, voids may form at the connection between the solder ball and the via pad, thereby causing increased electrical resistance. Further, the degraded connection between the solder ball and the via pad is more likely to fail over time due to thermal cycling. Additionally, water vapor or other gases or fluids may enter the via, causing corrosion of the conductive plating of the via or other damage to the via structure.